Two major complications of Acquired Immune Deficiency Syndrome (AIDS) are the development of malignancies and opportunistic infections. The basic hypothesis to be tested is that immunosuppression observed in AIDS associated with certain gay men is related to the introduction of semen via the alimentary tract through homosexual activities. We propose to determine if seminal plasma will result in alternations in host-resistance to viral infections and neoplasia induction and expression. The specific aims of this project are: 1) to determine the role of seminal plasma inoculation via the oral and GI routes in producing primary immune-deficiency, 2) to determine the susceptibility of mice to acute and latent CMV infections following seminal plasma administration, 3) to determine if seminal plasma and CMV infections have a synergistic effect on reducing immune function, and 4) to determine the role of seminal plasma on tumor expression, progression, metastases and mortality. Briefly, the methodology involves evaluating immunologic and host resistance studies following dose response assays with seminal plasma separately and with CMV. The immunological parameters to be measured in normal animals and animals given seminal plasma and virus are: 1) natural killer cell activity, 2) the specific immune response of spleen cells to a thymus dependent antigen measured precisely by the Jerne plaque assay and 3) the polyclonal activation of lymphocytes by mitogens. The host resistance parameters to be measured in mice administered seminal plasma is the pathogenesis of CMV infection. Also the susceptibility of mice to CMV infections and tumor induction will be determined by classical LD50 studies. The long term objectives (not included with the work scope of this proposal) are: 1) to define the suppressive factor(s) associated with semen, 2) to develop an in vitro assay for it, and 3) to exploit the suppressor factor(s) for human health benefits.